1. Field of the Invention
The invention concerns a device for sealing the gap between the rotor blades and the casing of a turbomachine, configured with a conical profile, in which the rotor blades are fitted with circumferential shroud plates, which seal with serrations against the casing with the formation of radial gaps.
2. Discussion of Background
Devices of this type are known. They consist essentially of shroud plates with serrations running in the circumferential direction and sealing against the casing or against a honeycomb arrangement. In this manner they form a see-through or a stepped labyrinth with purely radial gaps. As a rule, these shroud plates extend over the whole of the blade axial chord. A known sealing configuration of this type is represented by the second stage rotor blade in FIG. 1, which will be described later. For the mechanically and/or thermally highly loaded rotor blades in the last stage of a gas turbine, for example, such a solution is no longer possible with conventional materials. Help is provided in the classical tip sealing configuration by a damping device situated in the main flow. Such a damping device, which can for example be a damping wire, is absolutely essential for free-standing long blades with low natural frequencies. However, blades with tip sealing and means for vibration prevention have the disadvantage of large energy dissipation at the damping wire and in the tip sealing configuration.